Preparation of Cod Liver Residues and Vitamin B12 Concentrates
As the first part of an investigation of the nutritive value of cod liver, two methods of preparation of cod liver residue were studied, as well as the effect of drum drying the residue, with and without the presence of sodium bisulphite, defatting the dried residue and extracting vitamin B12 from the dried residue.It was found that Vandenheuvel's method of preparation of residue produces very good results. The fresh residue could be dried without appreciable loss of vitamin B12 activity on a double drum dryer, operated with steam at 20 p.s.i.g. Sodium bisulphite afforded some protection during the drying. The most satisfactory results in defatting were obtained by extraction with dichloroethylene. Concentrates with vitamin B12 activity equivalent to 2–4 micrograms per milliliter were produced by extraction of dried, defatted residue with water and evaporation in vacuo.Five different types of residue were prepared for further studies.